System Adjustments of Cummins Engine Single Unit Governor

System Adjustments of Cummins Engine  Single Unit Governor

Panel Mounted Governor Control Adjustments

The panel mounted governor control has four potentiometers for making system adjustments. These components are mounted on the control which is located inside the engine instrument panel or generator control panel.

NOTE: When a two bearing generator or a single bearing generator with a flexible drive between the flex discs and shaft (eg. Kohler 4T10 generators. Models 230ROZ, 250 ROZ and 275ROZ) is installed, use a remote mounted control. If the engine is not stable after the gain adjustment is made, install a jumper wire between terminals A and B.

The gain control is a one-turn potentiometer. It is used to adjust the sensitivity of the governor. A clockwise rotation of the potentiometer dial will shorten the response time of the governor to load changes. Refer to the glossary for the gain drescription.

The droop control is a one-turn potentiometer. It is adjustable for zero % (isochronous) to five % speed droop. Counterclockwise rotation will decrease the speed droop.

The idle speed controi is a 20-turn potentiometer for adjusting the idle speed. A clockwise rotation will increase the idle speed.

The run speed control is a 20 turn potentiometer for setting the desired no-load governed speed. A clockwise rotation will increase the run speed.

An idle-run switch, located on the engine instrument panel, allows the selection of the idle or run mode.

Also located on the engine instrument panel is the Speed Adjust potentiometer which is used for fine speed ajustment after Run Speed, Droop, and Gain have been set.

The panel mounted governor control wiring.

Caution: Measure the voltage on the engine control circuit board terminal strip and not on the control terminal strip. If two terminals on the control terminal strip are shorted, it can damage the control unit.

Preliminary Adjustments

The idle speed potentiometer adjustment.

1. Turn the screw counterclockwise 20 turns.

2. Turn the screw clockwise 10 turns.

3. This will set the idle speed potentiometer to its mid position.

The run speed potentiometer adjustment. 

This will set the run speed potentiometer to its mid position. (Firs and second points are same to idle speed.)

Turn the gain potentiometer adjustment to midposition or 50.

The droop potentiometer adjustment.

1. Turn the potentiometer fully counterclockwise for isochronous operation.

2. Turn the potentiometer to approximately 40 for 3 percent droop.

3. Turn the potentiometer to approximately 80 for 5  percent droop.

Adjust any remote speed potentiometers to the center of their adjustment range.

Governed Speed Adjustment

Place the idle-run switch on the engine instrument panel in the idle position.

NOTE: Open the main line circuit breaker while the engine is at idle.

Start the engine. Adjust the idle speed potentiometer the governor control until the engine i:s running at 600 to 650 RPM.

Generators which are to operate at 60 Hz full load, must have the engine no load governed speed adjusted to:

60.0 Hz (1800RPM) for

isochronous operation

61.8 Hz (1854 RPM) for

30/o speed droop

63.0 Hz (1890 RPM) for

5% speed droop

For generators which are to operate at 50 Hz full load, the engine no load governed speed must be adjusted to:

50.0 Hz (1500 RPM) for

isochronous operation

51.5 Hz (1545 RPM) for

3% speed droop

52.5 Hz (1575 RPM) for

5% speed droop

Move the idle run switch to the "Run" position. 

Adjust the run speed potentiometer on the governor control until the no load speed is correct.

NOTE: Close the main line circuit breaker.

Droop Adjustment Isochronous Operation

For isochronous operation, the droop potentiometer must be turned fully counterclockwise and will not require any further adjustment.

Gain Adjustment

Close the main line circuit breaker and apply approximately 1/4 of the rated load. Make sure the engine speed is constant.

If the engine speed is constant, turn the GAIN potentiometer clockwise slowly until the engine speed is not constant.